Can I use NDSR to calculate HEI scores?
HEI scores may be calculated using variables available in NDSR output files. To facilitate generating HEI-2015 scores we have created SAS programs that allow for calculating HEI-2015 scores. The following guide is available to support you in using the SAS code for calculating HEI-2015 scores.
Note: This guide is most relevant to those using NDSR 2015 or a subsequent version of the program. Contact NCC if you are interested in calculating HEI scores using versions prior to NDSR 2015.
Can NDSR be used to estimate intake of FODMAPs (fermentable oligo-, di-, and monosaccharides and polyols)?
How does the NCC Food and Nutrient Database compare to other databases?
How does NCC impute nutrients?
To minimize the number of missing values, NCC uses several standardized procedures to impute or logically calculate an estimation. These procedures are described in Procedures for estimating nutrient values for food composition databases. To summarize, one of the following procedures is employed to estimate a nutrient value for a food when an analytic value is not available from the USDA Nutrient Data Laboratory or cannot be found in the literature:
- Value from a different but similar food is used. (e.g., missing nutrient for wild duck may be judged to be the same as known nutrient in domestic duck)
- Value for another form of the same food is calculated (e.g., convert from raw to cooked values using retention factors)
- Calculate values from other components in the same food (e.g., estimate beta-carotene from Vitamin A)
- Calculate value from household recipes or commercial food product formulations for multicomponent foods (e.g., Manufacturers may provide ingredient listing and macronutrient composition of product. From the macro-nutrients, NCC database scientists estimate the amount of each ingredient. Based on the estimated amounts of the ingredients, micro-nutrients can be imputed for the product.)
Missing values are allowed in the database for foods that are consumed in very small quantities, such as spices, or where there are no data to indicate whether the nutrient exists in the food.
Some nutrients have no missing values, but a high percentage of imputed values. An example is Vitamin A which is calculated from provitamin A carotenoids and retinol.
In future versions of the database, missing and estimated values will be replaced by analytic values as they become available.
How does NCC assign nutrient values to unknown foods, and how can I figure out what food is being used as the 'default' for unknown foods?
To assign nutrient values to unknowns NCC uses the nutrient values for the form of the food that is believed to be most commonly consumed in the U.S. For example, the nutrient values for 2% milk are utilized for ‘milk, unknown % fat’. To decide what is most common, NCC relies on scientific and food industry publications that report dietary intake patterns and product sales. Professional judgment is also used where published data is lacking.
If you need to know what food an unknown food defaults to you can look in the output files. The Food File (output file 02) lists the food as it was selected (e.g., milk, unknown % fat). The Component/Ingredient File (output file 01) lists the default food that is associated with the unknown food (e.g., milk, 2 % fat). To quickly identify unknown foods in your dataset use the column in file 2 labeled ‘Unknown (default) Food’. If a food is an unknown there will be a ‘1’ in this column.
How does NCC decide whether to add new nutrients or food components to the database?
- Scientific Interest: Is there demand for it? If there is a nutrient or food component you’d like added to the database please let us know(firstname.lastname@example.org).
- Availability of Food Composition Information: Is there analytic composition information available for a significant proportion of core foods in the NCC Food and Nutrient Database?
- Quality of Analytic Data: Is the analytic information available of sufficient quality (e.g., obtained using appropriate analytic methods) for use in assigning values to foods in the NCC Food and Nutrient Database?